The writer speaks of God as if he were a place where people can go for safety. AT: "God gives us safety and strength" (See: [[rc://en/ta/man/translate/figs-metaphor]])
The writer speaks of the deepest part of the sea as if it were the sea's heart. Here he describes an earthquake that causes the mountains to crumble and fall into the sea. This can be stated in active form. AT: "the mountains should shake so violently that they fall into the depths of the sea" (See: [[rc://en/ta/man/translate/figs-metaphor]] and [[rc://en/ta/man/translate/figs-activepassive]])
The phrase "their swelling" refers to the waters of the sea as they rise and crash against the mountains. AT: "the swelling waters cause the mountains to tremble" (See: [[rc://en/ta/man/translate/figs-explicit]])